Radioactive Tuna?

Bluefin Tuna, caught in California last August, showed radiation levels that were ten times the norm, according to a new paper from the Proceedings of the National Academy of Sciences journal. Scientists believe that the radiation -- in the form of the isotopes, caesium-137 and caesium-134 -- came from the Fukushima Daiichi nuclear disaster that began in March of 2011.

The rates of caesium-137 and caesium-134 were elevated about 3 percent, compared to previous years in muscle samples taken from 15 two-year-old bluefin tuna caught off the coast of San Diego, Calif.

"That's definitely the mark of Fukushima," David J. Brenner, director of the Center for Radiological Research at Columbia University and a leading expert on the nuclear power plant meltdown who was not involved in the study, told The Huffington Post. "Most likely, the [tuna] would have eaten some contaminated fish off the coast of Japan and then swam across the Pacific ocean."

“That’s a big ocean. To swim across it and still retain these radionuclides is pretty amazing,” lead researcher Nicholas Fisher told the AP.

Indeed, from a long-term, population standpoint, the existence of Fukushima's radioactive material in our oceans, food chain and environment may be a cause for concern. But that doesn't mean that the radiated fish are necessarily a cause for health concern.

First, the elevated levels still remain well below the U.S. government's regulatory limits. And, as Brenner explains, we already get a great deal of radiation exposure in our foods, all naturally occurring. In fact, according to the data, rates of caesium-137 and caesium-134 are 35 times less than the amount of radioactive potassium, which is naturally-occurring in the fish. Radioactive potassium, along with polonium-210 are the two most common and largest radioactive compounds in our foods, but even these give off far less radiation than other natural sources we are exposed to on an annual basis: radon, which occurs naturally in soil and rock, and cosmic rays.

All of this may be a moot point, as Bluefin tuna eaten by Americans is usually farmed, according to seafood distributors interviewed by the San Francisco Chronicle. What's more, the fish that were used in this research were caught for sport, not for food.